The present invention relates to a method for synchronizing the sensor movement of a pitch and/or concentricity measuring device for gears, wherein at least one sensor is inserted radially into the gap between the teeth of the rotating gear to be tested and is carried along by the gear tooth for a section so as to measure the pitch and concentricity of the gear and, after the measurement, is automatically retracted, the waiting period of the sensor in its retracted position and the renewed insertion into the next tooth gap being controlled by a computer which is coupled with a timer. The invention also relates to an apparatus for implementing this method.
Pitch and/or concentricity measuring devices for gears have in the meantime been substantially automatized with respect to the measuring process. Thus it is known from DE-OS No. 2,123,960, laid open Feb. 17th, 1972, to feed the measured values to an electronic evaluation device which, from the individual measured values, calculates the absolute pitch errors, jumps in pitch and the sum pitch error. It is further known from DE-AS No. 2,412,574, published Mar. 16th, 1978, to provide a pitch measuring device with a process memory which not only performs the error evaluation but also controls the movement of the sensor in dependence on the rotary movement of the gear to be tested.
A basic drawback of these prior art devices is, however, that at the beginning of the measuring process, an operator must manually synchronize the lateral or radial sensor movement with the rotary movement of the gear to be tested so that it is assured that the advancing sensor enters into a gap between the teeth and does not abut against a tooth. Synchronization is effected in that the operator depresses a synchronizing key at the moment when the sensor faces a gap between two teeth, and this synchronizing key remains depressed until the next tooth gap is in front of the sensor. This manual synchronization process requires good visual acuity and fast reaction, particularly if the gaps between teeth are relatively small or if the gears are mounted on relatively fast moving turntables.
The same applies for all other known pitch and/or concentricity measuring devices (for example DE-PS No. 1,432,570, issued Aug. 26th, 1971) if they are used for gears having different dimensions.